why i need to upgrade html5

hello sir,
why i need to upgrade html5 even i am strong in html4?
what features of html5 discussed in Learning html5 game programming book?
are you discussed these things in your book?
moving things
canvas
3D landscope
Geolocation
Dynamic Content Injection
Video Destruction
Gravity features just like google gravity
microdata features
is it supports web storage.

Dynamic Content Injection
i mean of this is without using any scripting languages can we inject our content based on client request in pages..
Video Destruction means
in a video when we are going to next frame previous frame is destroyed just like specified in video editing tools